Is the risk of cancer reflected in the nails?

Nicotine levels in the nails can predict quite accurately the risk that a smoker and a non-smoker passively exposed to smoke have of developing lung cancer in the future. It is the conclusion of a study carried out at the University of California, San Diego, and published in the American Journal of Epidemiology .

Research revealed that individuals with the highest levels of nicotine in their nails were 3.5 times more likely to develop lung cancer than those with the lowest levels. According to scientists, nicotine levels in nails are relatively stable compared to urine or saliva. Toenails, which grow very slowly (one centimeter a year), reflect an individual's chronic exposure to tobacco smoke.

The scientists followed the participants for 12 years to see who developed lung cancer. The results showed that those who developed the disease had, at the beginning of the study, an average nicotine level of about 0.95 nanograms per milligram. In addition, more than 10% of the men with the highest levels of nicotine had never smoked, so the analysis also shows the "hidden risks" that passive smokers have.